We are a small tooling manufacturing company recently certified to AS9100. Our current system for labeling shelf life containers is to mark them with a black sharpie. However expiration dates are often rubbed off or faded when the material drips out of the bottles or just from everyday handling. I'm looking for suggestions on the best way to mark containers with the expiration dates as no method seems practical. Labels would fall off; a stamp would not work on surfaces that are not flat, and the ink would likely rub off the same as a marker. What do other companies do to identify expiration dates when dealing with messy liquids? Our only thought now is to stick with the sharpies and just be alert enough to re-write dates when they get faded or rubbed off? But that in and of itself is a risk.